net: rtnetlink: ignore NETDEV_PRE_TYPE_CHANGE in rtnetlink_event()

Ignore the new NETDEV_PRE_TYPE_CHANGE event in rtnetlink_event() since
there have been no changes userspace needs to be notified of.

Also add a comment to the netdev notifier event definitions to remind
people to update the exclusion list when adding new event types.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/notifier.h

@@ -182,7 +182,10 @@ static inline int notifier_to_errno(int ret)
  *	VC switch chains (for loadable kernel svgalib VC switch helpers) etc...
  */
  
-/* netdevice notifier chain */
+/* netdevice notifier chain. Please remember to update the rtnetlink
+ * notification exclusion list in rtnetlink_event() when adding new
+ * types.
+ */
 #define NETDEV_UP	0x0001	/* For now you can't veto a device up/down */
 #define NETDEV_DOWN	0x0002
 #define NETDEV_REBOOT	0x0003	/* Tell a protocol stack a network interface

net/core/rtnetlink.c

@@ -1513,6 +1513,7 @@ static int rtnetlink_event(struct notifier_block *this, unsigned long event, voi
 	case NETDEV_POST_INIT:
 	case NETDEV_REGISTER:
 	case NETDEV_CHANGE:
+	case NETDEV_PRE_TYPE_CHANGE:
 	case NETDEV_GOING_DOWN:
 	case NETDEV_UNREGISTER:
 	case NETDEV_UNREGISTER_BATCH: